In semiconductor fabrication processes, miniature electronic devices are formed on semiconductor wafers. In general, various materials which are either conductive, insulating, or semiconducting are patterned, doped, or deposited in layers to form the integrated circuits. The completed semiconductor circuit device is usually referred to as a semiconductor.
Because of the extreme miniaturization of the electrical components in an integrated circuit, particulate contamination during any semiconductor processing step or the manufacturing atmosphere in general adversely affects the proper performance of the finished product. Additionally, these various processes produce chemicals and byproducts which must be effectively disposed of or recycled.
One such semiconductor manufacturing process is chemical etching. In general, an etching process may be utilized to form patterns and contact vias on a semiconductor wafer. The etching process is typically accomplished in a hood or in an enclosed reaction space. A vacuum is applied to the hood or space to remove and filter airborne contaminants and gaseous byproducts from the reaction space. Among the gaseous byproducts are chlorine, silicon-tetrachloride, boron, trichloride, and other inert gases.
Typically, a vacuum pump is utilized to remove air from the reaction space. The vacuum pump includes a blower and recirculated vacuum oil which is mixed with the air in the pump to remove reaction gases or particulates entrained in the air. These contaminants must then be removed from the recirculated oil and disposed of or, in the case of gases, exhausted. The oil filtration and exhaust apparatus of the present invention is directed to such a filtration system for removing and disposing of contaminants formed during semiconductor manufacturing processes.
A first consideration in such filtration systems is that it is important that essentially all of the gaseous byproducts and particulates be removed from the recirculating oil. Additionally, the exhausted gases must be effectively disposed of. This is typically accomplished by venting the exhausted gases into an exhaust conduit which directs the gases to a furnace for burning.
A problem with such exhaust gas is that it is often carried into the exhaust conduits with entrained solid and vapor material. This material builds up as a solid mass on the walls of the exhaust conduits and eventually completely plugs an exhaust conduit. During normal operation of such a filtration system in semiconductor manufacture, a 10" (I.D.) exhaust conduit, for example, may be reduced by solid build-up to a 6" (I.D.) conduit within a matter of weeks. This renders the exhaust conduit as inoperable and necessitates replacement of the conduit. This is an expensive and time-consuming process.
There is a need, then, in semiconductor manufacturing for an oil filtration and exhaust apparatus which effectively removes particulates and entrained gases from the recirculating oil of a vacuum pump. In addition, there is a need for a system in which particulates and vapor are removed from exhausted gases prior to disposal in an exhaust conduit.